Let's perform the differentiation: $\frac{\mathrm{d}}{\mathrm{d}x}\left(3x^5\right)$

ⓘ A constant factor stays in front of the derivative, (k*u)' = k*u': $\frac{\mathrm{d}}{\mathrm{d}x}\left(3x^5\right)$ = $3·\frac{\mathrm{d}}{\mathrm{d}x}\left(x^5\right)$■The derivative of x^n is n*x^(n-1): $\frac{\mathrm{d}}{\mathrm{d}x}\left(x^5\right)$ = $5x^4$

$3·5x^4$

ⅰ $3·5$ = $15$

▶Derivative:   $15x^4$